Internal-combustion engine.



J. DOUGLAS.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED NOV.23,1912.

Patented Sept. 1, 1914 4 SHEETS-SHEET 1.

J. DOUGLAS.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED 11017.23, 1912.

Patented Sept. 1,1914%.

4 SHEETSBHEET Z.

J. DOUGLAS.

Patented Sept. 1, 1914.

4 SHEETS-SHEET 3.

m Mom a J. DOUGLAS.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED NOV. 23, 1912.

1,109,518, Patented Sept. 1,1914.

4 SHBETSSHEET 4.

g M ym/{loo I /O 04/ QM i/bwm/w o 3 h I V W WM/woq/b UNITED. STATES PATENT ornion.

JOHN DOUGLAS, OF EAST. SHEEN, SURREY, ENGLAND.

INTERNAL-COMBUSTION ENGINE.

To all whom it may concern:

Be it known that'l, JoHN DOUGLAS, a subject of the King of England, residing in East Sheen, Surrey, England, have invented certain new and useful Improvements in Internal-Coinbustion Engines, of which the following is a specification.

This invention relates to internal combustion engines,

, One of the important objects of the present invention is to reduce the Weight for power developed of internal combustion en gines having either stationary cylinders or rotating cylinders.

The present invention relates to the type of internal combustion motor wherein two pistons are em loyed, one of which is'hollow and Works witliin the cylinder and the other works within the hollow piston, the space between the twopistons being employed as a pump-chamber to compress mixture and pass it to that end of the cylinder from which the hollow piston starts when making its working stroke.

The invention will be described as applied to an engine of this type having-the following well-known features 5- -The hollow piston has an extension that works in an extension of the cylinder and at that end of the iston-extension' are ports which communicate with other ports at the end of the cylinder-extension toward the completion of the compression stroke and are uncovered in the cylinder itself when the piston is approximately at the end of its Working stroke. A charge can thus be compressed between the hollow piston and the other piston ithin it and then passed under Jressure through .the piston-extension into t e working portion of the cylinder, the part provided between the two pistons constituting a pumpchamber. The charge is admitted to the pump-chamber through the ports at the end of the cylinder-extension when those in the piston-extension are brought to register with them, and escapes from the pump-chamber to the working portion of the cylinder when the ports in the piston-extension are brought into such working portion.

According to the present invention, the engine which is of the type described and may or may not have the other well-known features referred to, is characterized by the pum ,-chamber between the pistons being provided with ports near oueend for ad Specification of Letters Patent.

- Patented sept. 1, new.

Application filed November 23,1912. Serial No. 733,113. 1

mitting air only and elsewhere with ports for admitting mixture, so that the pure air is'kept at one end and can be discharged first into the combustion chamber for scavenging. Preferably the pump-chamber s arranged to compress alarger charge than is required for the cylinder, so that when a portion has been employed, for scavenging, a full charge at the proper pressure still remains in the cylinder. This feature in itself isnot new, but is useful in conjunction with other features of the engine constituting the subject-matter of the present invention. I

The invention further relates to construe: tional details hereinafter fully described with reference to the drawings and whereof the novel features are pointedbutin the claims.

- In the accompanying drawings z- Figure 1 is an elevation in partsecti'o-n of an engine with stationary cylinders; Fig. 2 shows a part of 111g. ion a larger scale; Fig. 3 is a diagrammatic view of a detail; Fig. 4 is a side elevation of an engine having rotating cylinders, and Fig. 5 is a section through the same, on the line 5--5 of Fig. 4.

Like letters indicate like parts throughout the drawings.

The engine shown in Fig. l is provided with two cylinders A, A supported by crank-chambers A A which are conveniently square in plan having openings back and front closed by plates whereof one is shown at A partly broken for clear= ness. The cylinder A with its parts is shown in central vertical section. but the cylinder A with its parts is shown in elevation. Each cylinder is surrounded by a square i'acket A providing water-spaces A and iaving openings at the sides closed by cover plates A.

The two cylinders and their respective parts are exactly alike so that for convenience the further description may be confined to the cylinder A. This has top and bottom extensions B and C respectively, the top one, B, of which conveniently closed at its end. W 'thin the cylinder is a hollow piston (Fig. 1) composed of three parts, a central part I) and two end portions D. The central porticn D has its ends turned over as at o. and the annular channel thus provided at each end is made to receive the heads of bolts J. the other ends whereof pass through shoul ders on the t nd portions l) and receive nuts ice --right through them.

in a plane transverse to the longitudinalaxis of the piston and situated approxi mately midway of the length of the same.

The hollow piston has on each portion D a hollow extension D which is closed at its end and has a sliding fit within the cylinder extensionsB and C respectively. The end of each extension carries two sets of packing rings I) that are separated by a series of orts D in the piston extension. Each cylinder extension also has a set of ports B C respectively'that register with the ports D when the piston-extension is fully advanced into the corresponding cylinder-extension. The ports B communicate with a channel B that has communication. with the atmosphere through the inlet port B (see cylinder A and the ports C similarly correspond with an annular channel C which has communication with the atmosphere by means of a port C (see cylinder A The pistonextension D 'that is toward the crank-shaft E carries beyond the piston-rings D and ports D a gudgeon-pin D for a connecting rod E that extends out beyond the piston and cylinder extensions and engages a crank E on the engine crank-shaft E.

Co-axia-lly Within the hollow piston is mounted a closed piston F connected by a central rod F to a yoke F The yoke is disposed beyond the end of that extension of the cylinder remote from the crank-shalt and the rodF passes through the closed end of the piston-extension and the corresponding closed end of the cylinder-extension to enable it to be secured to. the yoke F The arms of the yoke have secured to them r ds F one on each side of the engine cylinder, which pass down the sides and through cored portions of the cylinder wall. At the crank-shaft ends they are received in guides F The cylinder covers are secured by studs and nuts A A respectively and two of these at the top and two corresponding studs at the bottom are made hollow to accommodate the rods F which thus extend. These studs A thus constitute additional guides for the rods F The crank-shaft ends of the rods carry pins F that receive the ends of eccentric rods F. These rods are connected to eccentric straps F that surround eccentrics E on the crankshaft E. These eccentrics are disposed at an angle of 180 to the crank E that is engaged by the connecting rod E of the hollow piston and are set one on each side of the same. I

Each cylinder A and A has 'cast around it three enlargen'ients A A, and A respectively. These enlargements are hollow and communicating with them and the interior of the cylinder are ports A, A. and A respectively. Each port is cut throu h the. wall by a boring-tool so that it takes tie form of a continuous slot right around the interior of the cylinder, and the cylinder is strengthened at these parts by ribs A which are cast in such position that when the slot is cut they constitute bridge-pieces across the ports and serve to give the neces sary strength to the cylinder.

The interior of the hollow enlargement A communicates with an exhaust passage G, the interior of the hollow enlargement A communicates with a passage G that has connection with the carburetor and if desired with a suitable additional air inlet for providing an explosive mixture, and the hollow enlargement A communicates with a second exhaust passage G which may be connected with the exhaust passage G if desired.

The engine thus described is double-acting and works on the two-stroke cycle. \Vith the parts in the position shown in the lefthand portion of Fig. 1, that is to say, the cylinder A and its pistons, it may be assumed that the combustion chamber H which is at the upper end of one working portion of the cylinder A, contains an explosive charge under pressure ready to be ignited, and the pump-chamber, that is to say, the space within the hollow piston that lies above the piston F, is charged in the main with mixture, but the upper portion with pure air only. If the charge in the combustion chamber is now exploded, the hollow piston, D, D is forced downward on its working stroke and operates the crankshaft, the eccentrics E simultaneously moving the piston F upwardly. At the first movement the ports D and D are closed, the ports D by being covered by the piston F and the ports D by being moved down out of register with the ports 13 the charge in the pump chamber is thus compressed. Toward the end of the working stroke the ports A are uncovered by the shoulder of the hollow piston so that exhaust commences into the hollow enlargement A and thence to the passage G and shortly after the commencement of exhaust, the ports D are brought down below the extension B of the cylinder so that they register with the combustion chamber or working portion of the cylinder. The charge compressed within the hollow piston can thus escape into the work ing portion of the cylinder through the ports D and in doing so the upper portion lli) means of the charge which pure air only passes rapidly through the cylinder and makes its escape by the exhaustports, sweeping the remainder of the exhaust out with it. The parts are then in the position shown in the lower portion of the cylinder A where exhaust is taking place on the opposite side of the piston F and the movementof the two pistons is now reversed so that they begin to rccede from each other, the ports D being immediately closed by their being carried again into the extension B of the cylinder and the ports I) being covered by the piston F. Suction is thus created within the hollow piston until the ports I) are un covered when explosive mixture will be sucked in from the passage G through the ports A of the hollow enlargement of the cylinder and the ports D By the upward travel of the hollow piston the ports D are again brought to register with the ports P, in the cylinder extension B and thus pure air is sucked in through the port B with which the ports 13 communicate. This air lies at the top of the explosive charge in the hollow piston and does not get mixed with such charge to any appreciable extent. During the upward movement of the hollow piston the charge formerly introduced into the working portion of the cylinder has been compressed into the combustion chamber H, and the parts are once more in the position assumed at the commencement of operations, so that the cycle of operations is now repeated.

It will be understood that the engine being double-acting, the same cycle of events is taking place in the lower portion of the cylinder A whose piston performs its working stroke alternately with the upper portion of the cylinder. It will be seen that the movementof the pistons D, D and F in opposite phase, enable the pump-chamber to be made of greater capacity than the working-portion of the cylinder A, so that a surplus portion of the charge in the pumpchamb r-can be discharged for scavenging, such .cui plus portion preferably consisting of air only, and that the ports D serve to admit this surplus charge of air and also to discharge the contents of the pun'ipchamber into the working portion of the cylinder.

By providing suitable controlling valves for the port 13 and passage Gr and connecting these to a single operating member, the amount of pure air admitted may be varied at will in proportion to variations made in the amount of mixture admitted. Thus. in Fig. 3 a valve J controls the inlet B to the port B and a valve J is provided in a conduit Gr connecting the carburetor and air inlet with the passage G to admit mixture. If then the two valves J, J. are connected by a rack engaging with pinions on the valve spindles, movement of the rack will move both the valves simultaneously and by properly proportioning the passage-ways through the valves and by initially setting the \alves in connection with the rack at what is the proper proportion for full working, the mixture may be throttled and more air n'oportiomitely introduced until it' desired, the mixture can be cut oil altogether and air only circulated in and out of the engine.

The object of the packing-pieces d between the piston parts D, I) is to permit of adjustment of these parts so that they can be arranged to cover or uncover the ports A, A and A, exactly at the required moment; moreover, these ports being arranged to be cut by a boring tool can be positioned far more accurately than is possible where the ports are cast in the cylinder.

It should be observed that the mass movement of the piston l. with its appropriate parts, is made to-balance the mass movement of the hollow piston D, D with its appropriate parts, and these working in opposite phase, give a balanced engine.

Obviously many modifications may be made in this engine as to the arrangement of the ports and various details of the engine: thus for example the upper extension B of the cylinder and the passages 13 and G with their ports could be omitted and-the engine operated as a single acting engine using only the lower combustion chamber; but such and other modifications are common engineering practice and can be made without departing from the spirit of the invention.

In Figs. 4t and 5 an engine is shown that operates upon the same principle as that shown in Figs. l--3,but the cylinders are a rranged to rotate and the pistons instead of being one inside the other, both have sliding contact with the cylinder although one has an extension that can pass through the other; moreover the engine shown is a single acting one. .Each cylinder K has mounted in. it two pistons L, L respectively. The piston L has a hollow extension L that is closed at its end by a suction valve L and between the valve and the cylinder, ports L are provided in the extension. The tubular extension L communicates by ports I, with, the pump-chamber M that is lMOVltlQtl between the pistons L, L and these ports L are formed in a centrally disposed tubular stem L that is connected to the piston L but is closed by a partition L V'Vithin the tubular stem and between the partition L and the crank-shaft. a gudgeonjpin is mounted to receive a. connecting rod N that con'imunicates the motion of the piston to a crank N on a crank-shaft N The piston L hollow and has an open neck L through which the tubular stem L of the piston L can pass. Pivoted within the piston L on that side toward the crank-shaft are two connecting-rods N one on each side ofthe rod N and these are operatively connected with cranks N set at 180 to the crank N The explosive mixture is admitted to the crank-case through a passage-way N in the crankshaft and enters the pum 9-chamber through ports M in a portion oi the wall of the cylinder K that projects into the crank-case. The cycle of operations is the same as that already described with reference to the engine shown in Figs. 1-3 and exhaust takes place through ports M in the cylinder M when these are uncovered by the piston L. The amount of air admitted to the pump-chamber may be varied by adjusting the spring of the suction valve L to resist opening more or less strongly according to whether less or more air is required.

The engine shown is provided with seven cylinders the various pistons and connecting-rods of which all operate on to the one set of cranks, as clearly shown in the drawings. Obviously a greater or smaller number of cylinders may be provided according to requirements. 1

What I claim as my invention and desire to secure by Letters Patent is 1. In an internal combustion engine the combination of a cylinder, a working piston reciprocating therein, said piston constituting one wall of the combustmn chamber between it and the end of the cylinder,,a second a piston reciprocating in said cylinder and moving relatively to said first piston, an inlet port admitting a charge into the space between the two pistons, said space between the pistons being so proportioned relatively to the working portion of the cylinder that a larger charge can be compressed therein than is necessary to fill the working portion of the cylinder at a suitable pressure where by the surplus is available for scavenging without the pressure of the charge retained being reduced below the normal, and means for admitting the charge so compressed between the pistons into the working portion of the cylinder wherein said first pisto' operates. I

In an internal combustion engine the combination of, a cylinder, two pistons reciprocatin therein and moving relatively to one anot er, the space between the two pistons being so proportioned relatively to the working portion of said cylinder that a larger charge can be compressed therein than is necessar to fill sai working portion of the cylin er at a suitable pressure, an air inlet at one end and a mixture inlet at the other end of said space between the pistons, transfer and said working portion of the cylinder whereby the air and mixture are discharged separately thereinto and whereby only a portion of the pure air is permitted to escape.

3. An internal combustion engine comprising a cylinder formed with an extension or neck at the end adjacent to the crank shaft, a hollow piston provided with a hollow extension projecting through said cylinder extension adapted to carry the gudgeonpin to connect with said shaft; a second piston within said piston carried b arod extending through the other end of said cylinder remote from the crank-shaft, a yoke for said rod, ide rods forsaid yoke extending downwar 1y on-each'side of the cylinder to connect with the crank-shaft.

4-. An internal combustion engine com prising a cylinder formed with an extension having ports therein, a hollow piston provided with an extension for said cylinder, a piston within said hollow piston forming a pump-chamber, ports in said piston extension adapted to alternately register with the working portion of the cylinder, whereby air is admitted to said pump-chamber, ports-in said hollow piston adapted to be shut and opened by said second piston, said ports communicatin with a chamber, ports in the cylinder wal communicating with said chamber.

In testimony whereof I have signed m ports in said cylinder extension and witl i name to this specification in the presence of two subscribing witnesses.

JOHN DOUGLAS. Witnesses HARRY G. Hmor, L. G. Evns.

ports connecting said space 1 

